In order to improve the finishing accuracy of a tire, a method for manufacturing a pneumatic tire which utilizes a rigid core mold has been proposed in patent documents 1-2 for example.
In this manufacturing method, unvulcanized rubber members which become tire constructional members are applied in series on the outer surface of the rigid core mold, and a green
The tire constructional members are an inner liner, carcass ply, belt ply, sidewall rubber, tread rubber and the like.
The green tire is put in a vulcanization mold together with the rigid core mold and vulcanization-molded.
The rigid core mold is an inner mold. The vulcanization mold is outer mold.
The rigid core mold includes an annular core-mold main portion. The core-mold main portion has an outer surface equivalent to the inner surface of the tire. The core-mold main portion is split in a plurality of core segments.
After the vulcanization-molding, each core segment is pulled out inwardly in the tire radial direction from the vulcanized tire in series. Thereby, the rigid core mold is taken out through the bead portion side of the tire (Core-mold taking-out step).
As is commonly known, the cross-sectional shape of the inner surface of a pneumatic tire protrudes outwardly in the tire axial direction mostly in the sidewall portions.
In contrast, the width of the bead portions is less than the sidewall portions.
Accordingly, in order to take out the core segment from the tire, a particularly large force is required to pass through the bead portions.
In order to increase the production efficiency of the tire, it is necessary to save the labor to take out the core-mold main portion and to reduce the cycle time of the core-mold taking-out step.